There is a method of decreasing diameter of magnetic particles that constitute a magnetic recording medium, as one example of a method of increasing a recording density by a magnetic recording. However, the smaller the diameters of the magnetic particles that constitute the magnetic recording medium are, the more a thermal fluctuation increases. As a result, there is a possibility that a recording state is unstable. As one example of a method of preventing the increasing of this thermal fluctuation, there is a method of increasing a magnetic coercive force of the magnetic recording medium. On the other hand, a magnitude of a magnetic field generated by a magnetic head is limited, and thus there is a possibility that the recording to the magnetic recording medium is difficult or impossible due to the increasing of the magnetic coercive force of the magnetic recording medium.
Thus, a HAMR (Heat Assisted Magnetic Recording) method that is allowed to temporality decreasing the magnetic coercive force of the magnetic recording medium in the recording by forming a heat spot on the magnetic recording medium by using a light irradiated to the magnetic recording medium in the recording is attracting an attention. In the HAMR recording method, it is preferable that a diameter of the heat spot be small to be dozens of nanometers that is about same as a size of a recording mark. In order to form the heat spot having this micro diameter (typically, having a diameter that is equal to or smaller than a diffraction limitation), it is preferable to use a near-field light.
Thus, as a device using the near-field light, near-field light devices having various structures are proposed. For example, a Patent Literature 1 discloses a near-field light device that has: a semiconductor substrate including quantum dots; and a metal end (an output end) that is formed on the semiconductor substrate. A Patent Literature 2 discloses a near-field light device having a NFT (Near Field Transducer). A Patent Literature 3 discloses a near-field light device in which a layer-structured metal end (a metal antenna) for generating the near-field light is formed on a semiconductor substrate. A Patent Literature 4 discloses a near-field light device in which a metal end (a metal antenna) for generating the near-field light is formed on a semiconductor substrate through a dielectric layer.